Public Class Form1
    Public Shared Function GetPingMs(ByRef hostNameOrAddress As String)
        Dim ping As New System.Net.NetworkInformation.Ping
        Return ping.Send(hostNameOrAddress).RoundtripTime
    End Function
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If My.Computer.Network.IsAvailable Then
            Dim a As String
            a = GetPingMs(TextBox2.Text)
            Dim tb2 As String = " ( " + TextBox2.Text + " ) = "
            Try
                RichTextBox1.AppendText(Environment.NewLine + "Response time -" + tb2 + "" + a)
            Catch ex As InvalidCastException
            End Try
        Else
            MsgBox("No network")
        End If
    End Sub